Objective To assess the test‐retest reliability of the 10‐step stair ascent test, Timed Up and Go (TUG) test, and 10‐meter walking test under dual‐task conditions in patients with fibromyalgia. Design Test‐retest reliability. Settings Local fibromyalgia association and university facilities. Participants Thirty‐eight women with fibromyalgia. Interventions Not applicable. Main Outcome Measures Fear of falling and the number of falls in the last year were measured using a visual analogue scale. The 10‐step stair ascent test, TUG test, and 10‐meter walking test were conducted under single‐ and dual‐task conditions. The order between single‐ and dual‐task condition was randomized in both test and retest. Retest measurement was assessed the week following the test. Results The reliability of the performance on the 10‐step stair ascent test under dual and single conditions ranged between good (>0.75 to < 0.9) and excellent (≥0.9), but there were significant differences between test and retest. The reliability of the TUG is between good (≥0.75 to < 0.9) and excellent (≥0.9) under the dual‐task condition as well as moderate (≥0.5 to <0.75) and excellent (≥0.9) under the single‐task condition. The reliability of the 10‐meter walking dual‐task test is between moderate (≥0.5 to <0.75) and good (≥0.75 to < 0.9) under dual‐ and single‐task condition, respectively. Conclusions The TUG and 10‐meter walking tests are reliable for assessing mobility under the dual‐task condition in women with fibromyalgia. The performance on the TUG, 10‐step stair ascent, and 10‐meter walking test under single‐ and dual‐task conditions was significantly related to fear of falling. These results may help healthcare professionals and researchers to interpret the effect of interventions in women with fibromyalgia.